Grazing Strategies

Rick Nelson
Extension Educator, Ag/4-H

In recent reading I
came across what was identified as the most common mistake being made by those
who have implemented rotational grazing strategies. The answer is not
surprising: We tend to graze pastures too short and returning too soon.

I doubt that anyone
who rotates pastures has not made the mistake of overgrazing a particular
pasture at some point. Though easier to avoid in the spring when pastures are
growing faster than the livestock can consume them, as mid to late summer roll
around and forage growth slows, grazing pastures too short is hard to avoid
without some serious preplanning and the willingness to adjust management on
the fly.

Many articles are
dedicated to grazing systems and when to move animals to the next pasture The
adage of take half, leave half of the dry matter forage, remains a popular
foundation for acceptable pasture management; actual height to trigger a move
will depend on forage species. We all know what overgrazing looks like. We also
know that the consequences of grazing pastures too short are long lasting.

1. Removing too
much of the photosynthetic factory (leaves) severely limits the plant’s ability
to recover and regrow. This will set the stage for another round of overgrazing
the next time through the rotation.

2. The plant’s
ability to grow new tillers is compromised. Some species keep their carbohydrate
reserves in structures below ground, others keep them in the lower one-third of
the canopy and removing these storage structures limits the plant’s capacity to
generate new tillers and persist long term.

3. Weeds
proliferate when overgrazing occurs. Slowed plant growth and more exposed soil
can easily lead to higher populations of undesirable weed species.

4. Plant root
growth is severely impacted. Research studies show that overgrazed pastures
result in plants that have less root mass and that root mass being much
shallower. This limits the plant’s ability to take up both water and nutrients,
especially during periods of dry weather. Not leaving enough forage biomass can
cause drought-like conditions even where adequate amounts of rainfall.

5. Overgrazing
exposes more of the soil surface allowing for a higher degree of runoff, less
water infiltration, more soil erosion, and elevated levels of evaporation.
Adequate forage cover intercepts raindrops, which slows impact at the soil
interface and enhances water infiltration.

6. Animal
performance suffers as forage intake declines when pastures are overgrazed.
Milk production or gain can be impacted both short and long term if pastures
are not given an adequate recovery period after being overgrazed.

Overgrazing
pastures, especially during periods of dry weather or when carrying capacity is
pushed to the limit, is a common occurrence. Often it happens before realizing
the damage has been done. There are proven steps that can be taken to keep
overgrazing to a minimum or eliminate the problem all together.

Though it’s never
an option that livestock producers like to implement, pasture forage may need
to be supplemented with stored feed. In extreme cases, livestock might need to
be pulled off pastures until adequate recovery occurs. Another option is to
plant a percentage of pasture acres to annual warm- or cool-season species and
use these acres while perennial species recover and accumulate adequate growth.
This latter option needs to be planned well ahead of time.

Overgrazing still
remains the single biggest mistake in forage-livestock systems. A little
preplanning to avoid overgrazing can help the long-term productivity of both
forage and livestock.

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